Alternator Swap: 11AC to A127

It looks like one. They do look very similar to some heavy duty flasher units. The OE ones always had a sticker on them to avoid confusion.
If it's on JRW listed as a 3AW then that's what it should be.
 
harveyp6 said:
It looks like one. They do look very similar to some heavy duty flasher units. The OE ones always had a sticker on them to avoid confusion.
If it's on JRW listed as a 3AW then that's what it should be.
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THanks, again, Harvey. I'll let you know how it goes.
PeterZRH said:
It should be noted that 2 wires for this job is a very poor engineering solution. The reason being it can partially fail in a dangerous state. ie. if one of the pair become disconnected, then a single wire would take the full current. The better solution would be to wire the alternator to the battery with the single, heavy cable that runs to the terminal post. The Ford version of this alternator does exactly that with a large, single ring termination on the alternator itself.[/QUOTE
PeterZRH said:
It should be noted that 2 wires for this job is a very poor engineering solution. The reason being it can partially fail in a dangerous state. ie. if one of the pair become disconnected, then a single wire would take the full current. The better solution would be to wire the alternator to the battery with the single, heavy cable that runs to the terminal post. The Ford version of this alternator does exactly that with a large, single ring termination on the alternator itself.
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Peter: Considering this, would a reasonable solution be to use a single, large-gauge wire, attach one end to the battery post or solenoid, and split the other end into two attachments to the A127 terminal?. Also, if you do connect to the interior battery post, instead of directly to the solenoid, is there not still a single, possibly undersized wire bringing the electricity from the battery post to the solenoid? Thanks, Drew
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I don't think it would help much. The point of failure would likely be one connector coming adrift. That would explain the single "block" connector as that is safer than individual spades.
 
PeterZRH said:
I don't think it would help much. The point of failure would likely be one connector coming adrift. That would explain the single "block" connector as that is safer than individual spades.
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Got it. Thank you so much for your help. I will let you know how things go. Very much appreciated, Peter.
 
PeterZRH said:
The wiring diagram is actually wrong for my car. It doesn't have the 6RA relay - this was removed on late 11AC models. What I did in the end was run a new pair of 10AWG wires to the battery terminal post on the floor.

I made a new loom with the two heavy wires and a pigtail for the ignition light/feedback so none of the original wires were cut at all so completely reversible. I also added in the oil pressure wire as my car had a strip speedo (no oil pressure gauge) and was converted to the later instruments. The cable then is neatly routed inside the car instead of a single cable not in a loom across the engine bay.
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Hi Peter, I stumbled on your old post about alternators etc and thought I’d throw something out there in case you had any thoughts…
mine is an early 3500s (‘72 suffix A) and a short while back the ignition switch just fell apart behind the dash. I managed to bodge it back together as a get-me-by while waiting to find a replacement; the 6-lead ones seemed impossible to find but finally Wadhams had them, reproduction but exactly right and even colour coding spot on. Before the new one arrived the bodge repair gave up and it all fell apart again. I had the engine running with starter solenoid still engaged and the key doing nothing. Anyway, that was very brief so didn’t think it had caused any damage…..but, new ignition switch fitted, and I now have a constant ignition light on, ammeter showing a -ve and from a straight meter test zero coming from the alternator. Took the alternator off the car and spun it up on the bench with a drill and get a current from it so now I’m thinking something in the charging circuit is causing the fault. Someone said the ignition switch going to pieces could have caused damage somewhere….. I’m running out of head to scratch but wondering how and what to test to trace what’s doing this…Would the 3AW, if shorted out, cause a lack of charge? I’ve swapped the 4TR over to a spare and makes no difference…..Mine has an original 11AC unit btw…..

Geoff
 
Re using 2 leads from alternator output to main live wire - Porsche did exactly that in the early 928s with a 70A alternator, so its not unique. Agree that its not a good practice and If I ever upgrade my 18ACR I will also upgrade the feed wiring.
 
Good morning,

I have joined the conversation late so please excuse.

I am in the late stages of a major resto-mod of a '70 P6 3500S NADA.

I had the original alternator rebuilt but I am now eyeing all the wiring and relays with suspicion.

Why are there two alternator relays in the center dash console?

I am thinking about using the Delco 1 wire or similar? Curious why it was not mentioned; is there a problem with the mount?

The one wire uses just that - one wire to the battery. Would that leave some portion of the loom unpowered?

Thanks for any advice or comments.
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Fredi
 
Fredi: There's a member of this forum, Peter Broad (I think), who published a wiring diagram for making the switch from the 11AC to the A127. I did it with ease, and, I am no mechanic by any stretch of the imagination. Maybe he can help.
Best of Luck.
Drew
 
I beg to differ on the usefulness of a voltmeter. Some instruments readings should be used to watch for changes in behaviour, as well as an instantaneous reading. Changes in behaviour usually betray something negative occurring that will soon need attention. In my 08 Subaru I see 14.7V after startup, dropping away to 14.1v inside 15 mins. In the Rover (18ACR) I will be worried if I dont see a reading arounnd 14.2V just after startup. As an aside, having seen the pic of an A127 installed, here is my 18ACR on a 1270mm belt - why is it so far further out than the A127?
 

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Fredi,
The two relays in the centre console aren't related to the alternator. One is for the air con electrics the other is for Power windows. I forget which is which but the windows one also has a thermal cutout there as well. I don't think the air con one does. Note the pictures in the manual look identical...And they all just happen to be the same type 6RA

With regard the one wire: the ignition (alternator) light and possibly the Amp Gauge (and associated resistor bar) will need some thought
M
 
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JP,
The 18ACR has a deeper, plastic, rear cover which causes the plug to foul the rocker cover; so they changed the bracket to move it further out...longer belt will then move it further....

If you are using a shorter replacement alternator you could also change the bracket for the smaller 11AC bracket, making things a little more compact.
M
 
Thanks, will look into that when I get A127 to fit.
Its arrived. It has a 1/4" male spade in a cavity, and a bolt terminal labelled W, and another bolt labelled + I assume this last is an extra output connection, but do I need to connect something to the W point - warning light? The small spade tag is common with the + bolt.
thanks

The separate 1/4 spade tag on the 18ACR doesnt seem to connect to any other contact, where the separate spade on the A127 is common with the + marked bolt. The spade on the 18ACR was connnected to a 12v wire - can somebody please confirm (or NOT?) that I can tape off this wire and ignore the terminal .....or ?
 
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